Liver Biopsy Features May Help Distinguish Drug-Induced Autoimmune-Like Hepatitis From Idiopathic Autoimmune Hepatitis

Context.—: Drug-induced autoimmune-like hepatitis (DI-ALH) and idiopathic autoimmune hepatitis (iAIH) share similar clinical, biochemical, serologic, and histologic features. Differentiating between them is crucial for treatment and prognosis. Objective.—: To identify clinical and histologic factors that distinguish DI-ALH from iAIH and develop a predictive scoring algorithm. Design.—: We evaluated diagnostic laboratory data and histologic features from index liver biopsies of 14 well-characterized DI-ALH cases and compared them with those from 19 age- and sex-matched iAIH cases. Data included age, sex, autoantibodies (anti-nuclear antibody, anti-smooth muscle antibody), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), γ-glutamyl transferase, immunoglobulin G, and total bilirubin (T. Bili). Histologic evaluation included modified Ishak scores, histologic activity index (HAI), type of portal inflammation, zonality of lobular inflammation, plasma cell clusters, cholestasis, bile duct damage, ballooning degeneration, portal endothelialitis, central venulitis, ceroid macrophages, lobular disarray, polyglucosan inclusions, bile duct loss, and ductular reaction. Fibrosis was assessed by using the Scheuer and Ishak systems. Results.—: A scoring algorithm with weighted scores for ALT above 289.5 U/L, AST above 303.5 U/L, ALP above 119.5 U/L, T. Bili above 0.65 mg/dL, HAI above 9.5, zone 2 sparing, lobular disarray, ballooning degeneration, ceroid macrophages, central venulitis, and advanced Ishak fibrosis yielded a receiver operating characteristic area under the curve of 0.99, with an optimal cutoff score of 6.5 favoring DI-ALH. Conclusions.—: A scoring algorithm that incorporates specific liver biopsy findings, HAI, and liver biochemistry profiles effectively distinguishes DI-ALH from iAIH.